RE: 300RUM Throat Errosion
Big I agree on the "scrub em to much" theory. My Warbird has had 9 boxes run through it in 5 years. After the initial "break in" of 3 boxes, the gun has held great accuracy and continues to. But I have NEVER let the gun get hot, I ONLY scrub out/de copper the barrel once a season (after season when I put it in the safe until next fall) and I always run a clean, dry BoreSnake through the barrel one time after each time afield whether I fired it or not. (I began doing this with every single gun I own and you would be amazed at how clean they stay as a result.)
John Lazzeroni told me that you can double the life of a "super mag" barrel with a little common sense and by having the patience to let the gun cool between shots at the range. Everyone claims 1k to be the expected life of such guns but he says when properly cared for that one should expect at a minimum of 1500 rounds before any noticable wear that effects accuracy. And he likewise added that the life should really be closer too 2k rounds when properly and patiently cared for.
Race cars require some special effort and so should super mags, but nothing that is overly laborious or challenging.